Snap action switch



W. A. BIERMNN ETAL SNAI.l ACTION SWITCH Filed Hay 19, 1941 July 22,1942.

Patented' July 2s, 1942 i'rEo STATES 'rN OFFICE mtime -s'NAP Ac'rroNswi'rc Application May 19, i941, Serial No. 394,066 y (Cl. wila-6T) aola.

This invention relates to electric circuit interrupters, and moreparticularly to that type of interrupter commonly known in the art as asnap action switch and may be employed where a quick make and/or quickbreak of the electrical contacts is required.

Another object of the novel invention `is to provide a snap actionswitch which maintains 'a constant maximum contact pressure up to thebreaking point.

A still further object of the device of this invention lies in theprovisionof a circuit interrupter of the snap action type wherein thepivot point of the actuating member is moved when it is desired to breakthe circuit in order lto decrease the time interval between maximumcontact pressure and rio-contact contact pressure to a minimum.

A further important improvement lies inthe use of a device of thisinvention using a 'floating pivot lwhere it is imperative that theactuating means overtravel -or go beyond the actualadistance required tosnap the `switch from one posiwhich the time interval between maximumcontact pressure and no-contact pressurewould be zero.. Of course, it istheoretically impossible to have suchk a condition of zero time but thistime interval can be reduced to a minimum and it is a purpose of ourinvention to do this'. 'It isvwell lknown in the art that maximumcontact pres- ,sure is desired at all times up to the break point toprevent frying or burning of the contacts.

Our invention further resides in the Vcombination, construction andarrangement of parts shown in the accompanying drawing; and while wehave illustrated therein preferred embodi- Figure 3 is a verticalsectional view partly in elevation of a modified form ofthis invention.

Referring in detail to the drawing and more particularly to Figure 1,the illustrated embodimerit of our novel invention comprises a base YIIIwhich may be made of kany insulating material or plastic compositionsuch as Bakelite or the like. Removably secured to the base I0 is a`cover II which may be made of the same material as the base. A switchsupporting bracket I2 is securely mounted to the base Ill by tubularrivets I3! which are drilled and tapped for the reception I of conductorholding screws I4. Contact supports I5 and it which are made ofelectrical conducting material are also rigidly ysecured to the base Itby tubular rivets I3 which are tapped for the reception of screws I.Contacts Il which may be of 'any suitable material such as silver areriveted or otherwise securely fastened to the contact supports l5 and I6in some conventional manner.

Two upstanding posts I8 disposed on either side of the supportingbracket I2 and integral therewith or fastened thereto carry the switchblade designated generally by the numeral I9. vThe switcliblade I9 whichis in the form of a `leaf spring or resilient strip and which may bemade of any suitable electrical conducting material is securely xed tothe upstanding posts I8 by rivets 2li which are adapted to interengagethe posts I8 and support I2. A washer disposed'between the head of therivet 20 and the resilient stripl 1 i@ provides a more positive meansfor holding said resilient strip securely to the upstanding Y post i8.The switch blade or resilient strip I9 is comprised of a frontcantilever member 22 which carries the contacts 23, and a second or rearcantilever member 24 which carries the center actuating member 25. Thecenter member 25 is ments it is to be understood that the same are vsusceptible of modification and change without departing from the spiritof our invention.

In the drawing:

; Figure 1` is a top plan view o f the preferred iform. ofthe device ofthis invention with the 'cover rexnoved;

FlgureiZv is a vertical crossLsectionfpartly in an integral part of theswitch blade I9 in they present' embodiment but this is a matter ofmechancal expedient or productional advantage. f The center actuatingmember 25 is reinforced with a substantially non-resilient element 26 toform a rigid center member 30. The non-resilient element 26 is securedto the member 25 in any suitable manner such as rivets 4.

' The non-resilient element 26 and the resilient member 2,5 pivot aboutan imaginary axis 8 of the rear cantilever member 24 and are free tomove upwardly or downwardly, thereby providing a.

floating pivot for said member 30. Interpolated enlarged' button 42having a conical element 43'.

integral its lower end is securely attached to the stem 40 and limitsthe upward movement of said stem. The conical element 43 may be made tocontact the rigid member 30 and successfully actuate it,any placebetween a center line drawn,

transversely through the posts -I8 and the pivot point 6 of the rigidmember on the rear cantilever arm. A compression spring 44 is disposedbeneath the rigid actuating member 30 and'is in vertical axial alignmentwith the actuating stem 4I) and conical element 43. `The upperconvolutions of the spring 44 abut the rigid member 30 and the lowerconvolutions abut the supportting bracket I2. Both the upper and lowerconvolutions of the spring encircle integral projections of the members30 and I2 respectively to constrain the spring in position. Depressingthe stem 40 moves the actuating arm 25 downwardly and compresses thespring 44 disposed beneath said arm. The force built up in the spring 44urges the actuatingarm 25 upwardly to the position shown in Figure 2when the external force is removed from the stem 40.

The modied form of this invention comprises a base I8, and a cover 5|having a slot 52 in one of its ends thru which a rigid actuating arm 54extends. A supporting bracket I2, and contact supports I5 and I8 aremounted on the base I8 in the manner describedin the preferredembodiment of our invention. The supports I5 and I5 carry the contactsI1 which co-act with the contacts23 carried by the cantilever arm 22.Upstanding posts I8 which may be an integral part of the supporting armI2, or riveted thereto, carry the switch blade I 8, said switch bladebeing fixed to the posts in the same manner as hereinbefore set forth.The switch blade or resilient strip I9 has a front cantilever member 22and a rear cantilever member 24 to which is pivotally secured andintegral therewith a4 center actuating resilient strip I9, to which therigid member 54 is`l immovably connected rotates with the actuating arm54 when a force is applied 'at any point between the pivot axis of saidarm and an innite number of points to the left of said pivot axis asviewed in Figure 3. The pivot axis of this arm which pivots about therear cantilever may be found mathematically or empirically. The stops 38-and 39 are an integral part of the upturned element of the supportingarm I2 and limit the throw of the member 25 vertically.` A compressionspring 32 is disposed between the end of member 25 and the cantilevermember 22. The ends of the spring abut cupped shaped elements 33 whichare recessed for the reception of bearings such as 38 and 31.

Many of the parts shown in the modified form are interchangeable withsimilar parts of the preferred embodiment as indicated by the partshaving the same numeral in both forms of the invention. The majordifference in the two devices lies in the point of application of theactuating force to the actuating arms.

. A force applied to a predetermined point on the actuating arm ofeither embodiment of our invention will (referring to Figures 2 and 3)first move the pivot4 point about which th'e actuating arm theoreticallyrevolves and then the continued application of this force will bring theactuating arm and its supporting member into balance with the forcecomponents of the front cantilever member and the coiled spring. Afterequilibrium is reached the continued application of force will cause theswitch to snap across center.

Moving the pivot point of the actuating lever enables us to maintain amaximum contact pressure up to the breaking point of the circuit. Thisis because the toggle action of the actuating arm is delayed until thefinal snap action over center is required. The force applied to theactuating arm may be in the form of a manually operated button as shown,temperature responsive element and etc.'

Having described the invention, we claim:

l. In a device of the character described, a supporting bracket, aresilient strip mounted on the supporting bracket beyond its mid-point,and electrical contacts carried by one end of said strip and a rigidactuating member carried by the other end of said strip, a center memberfixed to said rigid actuating member, a spring interposed between saidcenter member and the resilient strip, actuating means for saidactuating spring, center member integrally related to saidV leaf springand secured to the non-resilient member and adapted to rotate therewith,means providing -a floating pivot for said non-resilient member, currentcarrying contacts carried by the other end of said leaf spring, acompression spring interposed between' said center member 'and the otherend of saidleaf spring, contact carrying supports having electricalcontacts thereon, said electrical contacts co-operating with the currentcarrying `contacts on said leaf spring to complete an electricalcircuit, stops associated with said supporting bracket.

3. A snap action switch comprising a supporting bracket having a leafspring secured thereto, said leaf spring having ends free to movevertically, a non-resilient actuating member hingedly attached to oneend of the leaf spring and free to rotate about one end of said leafspring, a center member secured to the non-resilient member, one of saidfree ends of said leaf spring providing a floating pivot for saidvnon-resilient member, current carrying contacts carried bythe other endof said leaf spring, a compression spring interposed between a pointadjacent one end of said non-resilient member and said leaf spring,contact carrying supports having electrical contacts thereon, saidelectrical contacts cooperating with the current carrying contacts onsaid leaf spring to complete an electrical circuit, stops associatedwith said supporting bracket.

4, A switch blade provided with a center member hingedly connectedthereto, a supporting bracket for said switch blade, a compressionspring interposed between said center member and one end of said switchblade and normally biasing the center member away from the switch bladeanon-resilient member carried by the other end of said switch blade andsecured to said center member, said non-rilient member being free torotate about a movable pivot axis and thereby provide a delayed toggleaction for disposed and movable in the same direction when y cantileversand free to move vertically to change the pivot axis of the actuatingmember, a spring interposed between 4 the actuating member and the othercantilever member whereby said cantilever member is biased to build up avertical component of force' in said cantilever member, contact carryingsupports cooperating with said last actuated with respect to saidsupporting bracket,

an actuating member carried by one of saidY different balanced coilconnected to the free en`d of one of saidI canti-i levers and free tomove vertically with said cantilever to change the pivot point of saidnon-resilient member, a center memr xed to said non-resilient member,external means for operating said actuating member, means disposedadjacent said actuating member tor returning said actuating member tonormal position, current carrying contacts carried by the othercantilever, a spring interposed 'between the center member and said lastnamed'cantilever member, contact .carrying supports having electricalcontacts thereon which .cooperate with the contacts carried by one oi'said cantilevers, stops for said actuating member.

, 8. In a device oi' the class described, the combination of-a switchsupporting bracket, a switch blade mounted on said supporting bracketand comprising two cantilever members acting -on opposite sides of thesupporting bracket, an actuating member hingedly connectedto one of saidcantilever members, a coiled spring interposed between said actuatingmember and the other of said cantilever members, means associated withsaid switch bladewto compensate for 'ings, electrical contacts carriedby on of said cantilevers, contact carrying suppoijs having contactsamxed thereto and cooperating'with the contacts on said cantilever,stopsfor said actuating member;

named cantilever member. and stops iorlimiting the vertical movement ofthe actuating member, means for rotating the actuating member.

6. In a device of the class described, the com bination of a switchsupporting bracket, a exible cantilever member on either side of saidbracket the free ends of 'which are adapted to move vertically, anon-resilient actuating erinconnected 9. In a device of the classdescribed, the combination. of a base, a cover having an opening thereinand adapted to nt the base, a switch supporting bracket mounted on thebase, a switch blade secured to the supporting bracket and forming airont and a rearcantilever member, said front and rear cantilever beinghingedly connected tol said switch supporting bracket, a

rigid actuating member. hingedly connected to the rear cantilever memberand having a movable'pivot axis, a spring between the rigid actutothefree end of one of said cantilevers and free to move vertically withsaid cantilever to change the pivot point of said non-resilientA member,center member xed to said resilient member, current carrying contactscarried by theother cantilever, a spring interposed between said centermember ,and the last named cantilever 7. In a device of the classdescribed, the comating member andthe iront cantilever member,

contacts carried by the iront cantilever member,

an external actuating pin extending through said cover and terminatingwithin said cover, means for returning said rigid actuating memberItoits normal position after the external actuating pin v is released, andstopsk for limiting the vertical .65 bination o! a switchsupportingbracket. a x'elsil-- ient cantilever member on either side ofrsaidtravel oi said rigid actuating member,

1 WILLIAM -crznarc n. zARwnm.-

